
PY139 is a single-pigment yellow-orange option, similar to Isoindolinone Yellow Deep (PY110) or Hansa Yellow Deep (PY65). (Those are the comparisons along the bottom, along with Benzimida Orange.) It is nontoxic, moderately lightfast, and available from three manufacturers that I could find: MaimeriBlu’s Gamboge Hue (above), Daniel Smith’s Isoindoline Yellow, and Roman Szmal’s Permanent Yellow.